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Show 1869.] ON THE GENUS MICRASTUR. 367 5. MICRASTUR LEUCAUCHEN. Falco leucauchen, Temm. Pl. Col. 306. Micrastur leucauchen, Strick. Orn. Syn. p. 123. Micrastur gilvicollis (adult.), Pelz. Orn. Nov. p. 10. Hab. Brazil; Bahia (Wucherer) ; Mato Grosso (Natt.). This Micrastur is immediately distinguishable from M. ruficollis by its grey back and by the entire absence (in the adult bird) of any rufous colouring upon the throat and breast. In specimens not quite mature there is a rufous tinge upon the breast, which has apparently caused the species to be confounded in most collections with M. ruficollis. As in the latter bird, the belly is regularly banded continuously down to the crissum. This character and its paler upper surface serve to distinguish it from M. gilvicollis. In his ' Planches Coloriees' (no. 306) Temminck has figured his Falco leucauchen, which has been regarded by most writers as being the young of the same author's Falco xanthothorax ( = Micrastur ruficollis, Vieill.). Temminck does not expressly say whether his figure was taken from a specimen in the Paris Museum or in that of Vienna, both of which he states contain examples of this bird; but according to Schlegel (Musee des Pays-Bas, Astur es, p. 51) Temminck's type is one of Natterer's specimens now in the Leyden Museum. To determine positively whether Temminck's figure is applicable to the young of the present species or to that of M. ruficollis, reference must be made to this type specimen, which we have not yet had an opportunity of doing. But to avoid the unpleasant necessity of giving a fresh name to the present bird, which is certainly a most distinct species, we propose for the present to use Temminck's name for it, bearing in mind that M . Pucheran, a very accurate observer, has stated that in his opinion naturalists have erred in considering Temminck's two names synonymous*. Three specimens of this Hawk, in the collection of Salvin and Godman, are from Bahia, and were received from Dr. Wucherer. An example which we regard as the adult, and of which we shall speak subsequently, was obtained by Natterer in Mato Grosso. 6. MICRASTUR GUERILLA. Micrastur guerilla, Cass. Proc. Ac. Phil. iv. p. 87, et Journ. Ac. Phil. vol. i. p. 295, t. 40; Bp. Consp. Av. p. 30. Micrastur concentricus, Scl. P. Z. S. 1856, p. 285. Micrastur gilvicollis, Scl. et Salv. Ibis, 1859, p. 218 ; Scl. P. Z. S. 1858, p. 96 ; Scl. P. Z. S. 1860, p. 96; Lawr. Ann. L. N. Y. vii. p. 317. Micrastur xanthothorax, Scl. P. Z. S. 1859, p. 368. Hab. Mexico, Jalapa (Cassin) ; Cordova (Salle) ; Guatemala (Salvin) ; Veragua (Arce) ; Western Ecuador, Nanegal (Fraser). W e have long been well acquainted with this Micrastur; Salvin obtained specimens of it in every stage of plumage during his expeditions to Guatemala, and it is also common in Mexican collections; * Eev. Zool. 1850, p. 91. |